Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge, roll or column of smokable material such as shredded tobacco (e.g., in cut filler form) surrounded by a paper wrapper thereby forming a so-called “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element comprises plasticized cellulose acetate tow circumscribed by a paper material known as “plug wrap.” Certain cigarettes incorporate a filter element having multiple segments, and one of those segments can comprise activated charcoal particles. Typically, the filter element is attached to one end of the tobacco rod using a circumscribing wrapping material known as “tipping paper.” It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air. A cigarette is employed by a smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.
The tobacco used for cigarette manufacture is typically used in blended form. For example, certain popular tobacco blends, commonly referred to as “American blends,” comprise mixtures of flue-cured tobacco, burley tobacco and Oriental tobacco, and in many cases, certain processed tobaccos, such as reconstituted tobacco and processed tobacco stems. The precise amount of each type of tobacco within a tobacco blend used for the manufacture of a particular cigarette brand varies from brand to brand. However, for many tobacco blends, flue-cured tobacco makes up a relatively large proportion of the blend, while Oriental tobacco makes up a relatively small proportion of the blend. See, for example, Tobacco Encyclopedia; Voges, E. (Ed.), 1984; pp 44-45, Browne, C. The Design of Cigarettes, 3rd ed.; 1990; p 43; and Tobacco: Production, Chemistry and Technology; Davis, D. and Nielsen, M. (Eds.); 1999; p 346.
Tobacco also may be enjoyed in a so-called “smokeless” form. Particularly popular smokeless tobacco products are employed by inserting some form of processed tobacco or tobacco-containing formulation into the mouth of the user. Various types of smokeless tobacco products are known. See for example, the types of smokeless tobacco formulations, ingredients, and processing methodologies set forth in U.S. Pat. No. 1,376,586 to Schwartz; U.S. Pat. No. 3,696,917 to Levi; U.S. Pat. No. 4,513,756 to Pittman et al.; U.S. Pat. No. 4,528,993 to Sensabaugh, Jr. et al.; U.S. Pat. No. 4,624,269 to Story et al.; U.S. Pat. No. 4,991,599 to Tibbetts; U.S. Pat. No. 4,987,907 to Townsend; U.S. Pat. No. 5,092,352 to Sprinkle, III et al.; U.S. Pat. No. 5,387,416 to White et al.; U.S. Pat. No. 6,668,839 to Williams; U.S. Pat. No. 6,834,654 to Williams; U.S. Pat. No. 6,953,040 to Atchley et al.; U.S. Pat. No. 7,032,601 to Atchley et al.; and U.S. Pat. No. 7,694,686 to Atchley et al.; US Pat. Pub. Nos. 2004/0020503 to Williams; 2005/0115580 to Quinter et al.; 2006/0191548 to Strickland et al.; 2007/0062549 to Holton, Jr. et al.; 2007/0186941 to Holton, Jr. et al.; 2007/0186942 to Strickland et al.; 2008/0029110 to Dube et al.; 2008/0029116 to Robinson et al.; 2008/0173317 to Robinson et al.; 2008/0196730 to Engstrom et al.; 2008/0209586 to Neilsen et al.; 2008/0305216 to Crawford et al.; 2009/0065013 to Essen et al.; 2009/0293889 to Kumar et al.; 2010/0291245 to Gao et al; and 2011/0139164 to Mua et al.; PCT WO 04/095959 to Arnarp et al. and WO 2010/132444 to Atchley; each of which is incorporated herein by reference.
One type of smokeless tobacco product is referred to as “snuff.” Representative types of moist snuff products, commonly referred to as “snus,” have been manufactured in Europe, particularly in Sweden, by or through companies such as Swedish Match AB, Fiedler & Lundgren AB, Gustavus AB, Skandinavisk Tobakskompagni A/S, and Rocker Production AB. Snus products available in the U.S.A. have been marketed under the tradenames Camel Snus Frost, Camel Snus Original and Camel Snus Spice by R. J. Reynolds Tobacco Company. See also, for example, Bryzgalov et al., 1N1800 Life Cycle Assessment, Comparative Life Cycle Assessment of General Loose and Portion Snus (2005). In addition, certain quality standards associated with snus manufacture have been assembled as a so-called GothiaTek standard. Representative smokeless tobacco products also have been marketed under the tradenames Oliver Twist by House of Oliver Twist A/S; Copenhagen, Skoal, SkoalDry, Rooster, Red Seal, Husky, and Revel by U.S. Smokeless Tobacco Co.; “taboka” by Philip Morris USA; Levi Garrett, Peachy, Taylor's Pride, Kodiak, Hawken Wintergreen, Grizzly, Dental, Kentucky King, and Mammoth Cave by Conwood Company, LLC; and Camel Orbs, Camel Sticks, and Camel Strips by R. J. Reynolds Tobacco Company.
Through the years, various treatment methods and additives have been proposed for altering the overall character or nature of tobacco materials utilized in tobacco products. For example, additives or treatment processes have been utilized in order to alter the chemistry or sensory properties of the tobacco material, or in the case of smokable tobacco materials, to alter the chemistry or sensory properties of mainstream smoke generated by smoking articles including the tobacco material. Various types of enzymes, bacteria, and microorganisms (e.g., fungi and yeast) have been employed in conjunction with tobacco for the purpose of altering the chemical makeup of the tobacco, e.g., by reducing the content of certain chemical compounds. See, for example, U.S. Pat. No. 3,132,651 to Keifer; U.S. Pat. No. 3,513,857 to Silberman; U.S. Pat. No. 3,240,214 to Bavley; U.S. Pat. No. 3,636,097 to Harvey; U.S. Pat. No. 3,612,065 to Rosen; U.S. Pat. No. 3,943,945 to Rosen; U.S. Pat. No. 4,135,521 to Malan; U.S. Pat. No. 4,140,136 to Geiss et al.; U.S. Pat. No. 4,151,848 to Newton et al.; U.S. Pat. No. 4,307,733 to Teng; U.S. Pat. No. 4,308,877 to Mattina et al.; U.S. Pat. No. 4,407,307 to Gaisch; U.S. Pat. No. 4,476,881 to Gravely et al.; U.S. Pat. No. 4,556,073 to Gravely et al.; U.S. Pat. No. 4,557,280 to Gravely et al.; U.S. Pat. No. 4,566,469 to Semp et al.; U.S. Pat. No. 4,572,219 to Gaisch; U.S. Pat. No. 4,709,710 to Gaisch; U.S. Pat. No. 4,716,911 to Poulose; U.S. Pat. No. 4,887,618 to Bernasek; U.S. Pat. No. 4,941,484 to Clapp; U.S. Pat. No. 5,099,862 to White; U.S. Pat. No. 5,343,879 to Teague; U.S. Pat. No. 5,372,149 to Roth et al.; U.S. Pat. No. 5,601,097 to DeGranpreet; U.S. Pat. No. 7,549,425 to Koga et al.; U.S. Pat. No. 7,549,426 to Koga et al.; and U.S. Pat. No. 7,556,046 to Koga et al.; Int. Appl. Publ. No. WO 2000/02464 to Kierulff; and EP Appl. No. 1094724 to Kierulff, which are all incorporated herein by reference.
Nitrosamines are known to be present in air, foods, beverages, cosmetics, and even pharmaceuticals. Preussman, R. et al., In Chemical Carcinogens, 2nd ed., Vol. 2, Searle, C. E. (Ed.); ACS Monograph 182; 1984; pp 829-868. Tobacco and tobacco smoke also are known to contain nitrosamines. Green et al. Rec. Adv. Tob. Sci. 1996, 22, 131. Tobacco is known to contain a class of nitrosamines known as tobacco specific nitrosamines (TSNAs). Hecht, S. Chem. Res. Toxicol. 1998, 11, 6, 559-603; Hecht, S. Mut. Res. 1999, 424, 1-2, 127-142. TSNAs have been reported to be present in smokeless tobacco, Brunnemann, K. et al. Canc. Lett. 1987, 37, 7-16, Tricker, A. Canc. Lett. 1988, 42, 113-118, Andersen, R. et al. Canc. Res. 1989, 49, 5895-5900; cigarette smoke, Spiegelhalder, B. et al. Euro. J. Canc. Prev. 1996, 5, 1, 33-38; Hoffmann, D. et al. J. Toxicol. Env. Hlth. 1997, 50, 307-364; Borgerding, M. et al. Food Chem. Toxicol. 1998, 36, 169-182; nicotine-containing gum, Osterdahl, B.-G. Food Chem. Toxic. 1990, 28, 9, 619-622; and nicotine-containing transdermal patch, Adlkofer, F. In Effects of Nicotine on Biological Systems II, Clarke, P. et al. (Eds.); 1998, pp 17-25.
Green and freshly harvested tobaccos have reported to be virtually free of TSNAs. Parsons, A. Tob. Sci. 1986, 30, 81-82; Spiegelhalder, B. et al. Euro. J. Canc. Prev. 1996, 5, 1, 33-38; Brunnemann, K. et al. J. Toxicol.-Clin. Toxicol. 1982-3, 19, 6&7, 661-668; Andersen, R. et al. J. Agric. Food Chem. 1989, 37, 1, 44-50; Djordjevic, M. et al. J. Agric. Food Chem. 1989, 37, 752-756. However, it has been observed that TSNAs form during the post-harvest processing to which tobacco is subjected. Tricker, A. Canc. Lett. 1998, 42, 113-118; Chamberlain, W. et al. J. Agric. Food Chem. 1988, 36, 48-50. TSNAs are recognized as being formed when tobacco alkaloids, such as nicotine, are nitrosated. Hecht, S. Chem. Res. Toxicol. 1998, 11, 6, 559-603.
Significant efforts have been expended towards studying the mechanism of TSNA formation during tobacco curing. For example, it has been postulated that TSNAs form during the air-curing of Burley tobacco as a result of microbial mediated conversion of nitrate to nitrite, and the subsequent reaction of nitrate-derived chemical species with alkaloids present in the tobacco. Hamilton et al. Tob. Sci. 26, 133-137 (1982); Burton, H. et al. J. Agric. Food Chem. 1992, 40, 1050-1055; Bush et al., Coresta Bulletin Information 1995, Abstract, 9814; Wiernik, A. et al. Rec. Adv. Tob. Sci. 1995, 21, 39-80; Cui et al., TCRC (1996); deRoton, C. et al. Beitrage Tabakforsch. Int. 2005, 21, 6, 305-320; and Staaf, M. et al., Beitrage Tabakforsch. Int. 2005, 21, 6, 321-330. Additionally, for example, it has been postulated that TSNAs form during the flue-curing of Virginia tobaccos due to interaction of those tobaccos with nitric oxide combustion products present in exhaust gases produced during use of so-called direct-fired flue-curing barns. U.S. Pat. No. 7,404,406 to Peele and Nestor et al. Beitrage Tabakforsch. Int. 2003, 20, 467-475; see also U.S. Pat. No. 7,650,892 to Groves et al.
It would be desirable in the art to provide further methods for altering the character and nature of a plant such as a tobacco plant, as well as tobacco compositions and formulations useful in smoking articles or smokeless tobacco products.